The following abbreviations are herewith defined, at least some of which are referred to within the following description of the state-of-the-art and the present invention.    DBA dynamic bandwidth allocation    DSL digital subscriber line    DSLAM DSLaccess multiplexer    FEC forward error correction    GE gigabit ethernet    GEM GPON encapsulation method    GPON gigabit PON    LT line termination    MAC media access control    NR-DBA non-status-reporting DBA    NT network termination    OLT optical line terminal    PCS physical coding sublayer    PMA physical medium attachment    PMD physical medium-dependent    PON passive optical network    PP packet processing    ROSA receive optical sub-assembly    SFP small form-factor pluggable    SR-DBA status-reporting DBA    TOSA transmit optical subassembly
An access node is positioned between two portions of the communications network, typically the access network and the core network. The access node is, for example, a DSLAM or an OLT. An exemplary communications network having an access node is shown in FIG. 1. FIG. 1 is a simplified schematic diagram illustrating selected components PON (passive optical network) 100 in which an access node according to the present invention may be deployed. The access node in this case is OLT 101, which handles communications between a core network (not shown) and individual subscribers. Trunk lines 105 and 110 are high capacity lines for communications between the OLT 101 and the network core. Subscriber lines 116 through 119 carry communications to and from individual subscribers. As an example, access network line 118 extends between OLT 101 and splitter 120.
In this example, splitter 120 divides the downstream optical signal's constituent wavelengths for transmission to subscriber premises. Subscriber line 118 communicates through premises lines 121 through 126 are shown extending between splitter 120 and ONTs 130 through 135. Note that any upstream traffic from subscribers is not split in this fashion, but instead occurs according to a predetermined schedule where each subscriber is assigned specific time slots. Note that PON 100 is exemplary and network configurations may vary. There are a number of PON design evolutions including BPON, GPON, and XGPON.
FIG. 2 is a simplified block diagram illustrating selected components of an OLT 150 according to the existing art. The OLT 150 of FIG. 2 includes an NT (network termination) side and an LT (line termination) side interconnected by switch fabric 180. Note that that switch fabric 180 is represented only generally. On the NT side, boards 155 and 165 process upstream and down stream traffic between the switch fabric 180 and, respectively, trunk lines 150 and 160. Boards 155 and 165 are typically fabricated as a single unit that may be installed and removed from OLT 150. Each NT card 155, 160 includes a number of functions that represent operations that data traffic undergoes as it passes though the board in either the upstream or downstream direction. Note that these functions represented by abbreviations in FIG. 2 are known in the art and will not be explained in detail here. Note also that there may more or fewer NT boards than is represented in FIG. 2.
Similarly, LT boards 175a through 175n are shown in FIG. 2. LT boards 175a through 175n link subscriber lines 170a through 170n, respectively, with switch fabric 180. Although only four LT boards are shown in FIG. 2, the number of LT boards present is usually significantly higher. In some cases, each board may include multiple ports to accommodate subscriber lines although this is not depicted in the figure. As with the NT boards, each of the LT boards 175a through 175n include a number of traffic-handling functions analogous to those on the NT boards for handling the data traffic as it passes through the LT board in an upstream or downstream direction.
Unfortunately, access nodes designed and operated in this way have some disadvantages, especially an inefficient use of power. Boards having a variety of functions often require many different voltages and are kept fully powered, even though the nature of some transmission is bursty rather than steady. Most boards are run at a high clock speed regardless of traffic.
Accordingly, there has been and still is a need to address the aforementioned shortcomings and other shortcomings associated with access nodes in communication networks. These needs and other needs are satisfied by the present invention.